U.S. patent application number 16/072516 was filed with the patent office on 2019-01-31 for power transfer assembly with hypoid gearset having optimized pinion unit.
The applicant listed for this patent is MAGNA POWERTRAIN OF AMERICA, INC.. Invention is credited to Bradley Ketchel, Ralph Larson, Wade Smith, Ryan Strand.
Application Number | 20190031023 16/072516 |
Document ID | / |
Family ID | 58018348 |
Filed Date | 2019-01-31 |
View All Diagrams
United States Patent
Application |
20190031023 |
Kind Code |
A1 |
Ketchel; Bradley ; et
al. |
January 31, 2019 |
POWER TRANSFER ASSEMBLY WITH HYPOID GEARSET HAVING OPTIMIZED PINION
UNIT
Abstract
An integrated pinion/bearing/coupling (PBC) assembly for use
with a hypoid gearset in power transfer assemblies of motor
vehicles having mounting features and venting features, The
integrated PBC assembly includes a hollow pinion unit made of steel
and including a pinion shaft segment and a pinion gear segment, and
a coupling unit having a hub segment made of aluminum. A brazing
sleeve is used to braze the aluminum hub segment of the coupling
unit to the steel pinion shaft segment of the pinion unit.
Inventors: |
Ketchel; Bradley; (Oxford,
MI) ; Smith; Wade; (Mussey, MI) ; Larson;
Ralph; (Olivet, MI) ; Strand; Ryan; (Rochester
Hills, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAGNA POWERTRAIN OF AMERICA, INC. |
Troy |
MI |
US |
|
|
Family ID: |
58018348 |
Appl. No.: |
16/072516 |
Filed: |
February 8, 2017 |
PCT Filed: |
February 8, 2017 |
PCT NO: |
PCT/US2017/016896 |
371 Date: |
July 25, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62293611 |
Feb 10, 2016 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60K 17/165 20130101;
F16H 48/42 20130101; F16H 48/08 20130101; F16H 1/145 20130101; F16H
48/40 20130101; B60K 17/35 20130101; B60K 17/344 20130101; F16H
57/021 20130101 |
International
Class: |
B60K 17/16 20060101
B60K017/16; B60K 17/344 20060101 B60K017/344; B60K 17/35 20060101
B60K017/35; F16H 1/14 20060101 F16H001/14 |
Claims
1. A power transfer assembly for use in a motor vehicle,
comprising: a housing; a rotary input driven by a powertrain and
rotatably supported by the housing; a rotary output rotatably
supported by the housing and driving a pair of wheels; and a hypoid
gearset rotatably supported by the housing for transferring drive
torque from the input to the output and including a ring gear and
an integrated pinion/bearing/coupling (PBC) assembly, the ring gear
being drivingly interconnected to one of the input and the output,
the PBC assembly being drivingly connected to the other one of the
input and the output, the PBC assembly including a pinion unit, a
coupler unit, and a bearing unit, wherein the pinion unit is a
hollow steel component having a tubular shaft segment and a tubular
gear segment that is meshed with the ring gear, wherein the bearing
unit rotatably mounts the pinion unit for rotation relative to the
housing, and wherein the coupler unit includes an aluminum flange
having a tubular hub segment surrounding and rigidly secured to the
shaft segment of the pinion unit.
2. The power transfer assembly of claim 1, wherein the PBC assembly
further includes a brazing sleeve made of an intermediary material
and which is disposed between the hub segment of the aluminum
flange and the shaft segment of the steel pinion unit.
3. The power transfer assembly of claim 2, wherein the brazing
sleeve is made from copper.
4. The power transfer assembly of claim 1, wherein the PBC assembly
further includes a lock collar fixed to a bearing housing of the
bearing unit, and wherein the lock collar is configured to secure
the PBC assembly to the housing.
5. The power transfer assembly of claim 4, wherein the lock collar
includes external threads configured to engage internal threads
formed in the housing to permit adjustment of the PBC assembly
relative to the ring gear.
6. The power transfer assembly of claim 1, wherein the PBC assembly
further includes a vent assembly installed in the tubular shaft
segment of the pinion unit, and wherein the vent assembly functions
to vent pressurized air from within the housing to ambient.
7. The power transfer assembly of claim 6, wherein the vent
assembly includes a cap member mounted in an open end of the shaft
segment and which defines a vent aperture, a valve seat mounted in
the vent aperture, and a pressure-actuated plunger moveable
relative to the valve seat for controlling a flow of pressurized
air from within the housing to the ambient.
8. The power transfer assembly of claim 1, wherein the steel pinion
unit is formed as a one-piece component.
9. The power transfer assembly of claim 1, wherein the bearing unit
includes a pair of laterally-spaced bearing assemblies disposed
between the shaft segment of the steel pinion unit and a bearing
housing that is secured to the housing.
10. The power transfer assembly of claim 1 defining an axle
assembly such that the housing is an axle housing, wherein the
input is a propshaft drivingly connected to the aluminum flange of
the coupling unit, and wherein the output is a differential
assembly driven by the ring gear.
11. The power transfer assembly of claim 1 defining a power
take-off unit such that the housing is a PTU housing, wherein the
ring gear is drivingly connected to the input, and wherein the
output is a propshaft drivingly connected to the aluminum flange of
the coupling unit.
12. The power transfer assembly of claim 1, wherein the aluminum
flange of the coupling unit is brazed to the steel shaft segment of
the pinion unit via an intermediate sleeve made of copper.
13. A power transfer assembly for use in a motor vehicle,
comprising: a housing; a rotary input driven by a powertrain and
rotatably supported by the housing; a rotary output rotatably
supported by the housing and driving a pair of wheels; and a hypoid
gearset rotatably supported by the housing for transferring drive
torque from the input to the output and including a ring gear and
an integrated pinion/bearing/coupling (PBC) assembly, the ring gear
being drivingly interconnected to one of the input and the output,
the PBC assembly being drivingly connected to the other one of the
input and the output, the PBC assembly including a steel pinion
unit, an aluminum coupler unit, and a bearing unit, the pinion unit
having a tubular shaft segment and a tubular gear segment that is
meshed with the ring gear, the bearing unit rotatably mounts the
pinion unit for rotation relative to the housing, and the coupler
unit having a flange with a tubular hub segment surrounding and
rigidly secured to the shaft segment of the steel pinion unit.
14. The power transfer assembly of claim 13, wherein the PBC
assembly further includes a brazing sleeve made of an intermediary
material and which is disposed between the hub segment of the
aluminum flange and the shaft segment of the steel pinion unit.
15. The power transfer assembly of claim 13, wherein the PBC
assembly further includes a lock collar configured to secure the
PBC assembly to the housing, and wherein the lock collar includes
external threads configured to engage internal threads formed in
the housing to permit adjustment of the PBC assembly relative to
the ring gear.
16. The power transfer assembly of claim 13, wherein the PBC
assembly further includes a vent assembly installed in the tubular
shaft segment of the pinion unit, and wherein the vent assembly
functions to vent pressurized air from within the housing to
ambient.
17. The power transfer assembly of claim 13, wherein the steel
pinion unit is formed as a one-piece component.
18. The power transfer assembly of claim 13 defining an axle
assembly such that the housing is an axle housing, wherein the
input is a propshaft drivingly connected to the aluminum flange of
the coupling unit, and wherein the output is a differential
assembly driven by the ring gear.
19. The power transfer assembly of claim 13 defining a power
take-off unit such that the housing is a PTU housing, wherein the
ring gear is drivingly connected to the input, and wherein the
output is a propshaft drivingly connected to the aluminum flange of
the coupling unit.
20. The power transfer assembly of claim 13, wherein the aluminum
flange of the coupling unit is brazed to the steel shaft segment of
the pinion unit via an intermediate sleeve made of copper.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This International application claims the benefit and
priority of U.S. Provisional Application No. 62/293,611 filed Feb.
10, 2016. The entire disclosure of the above application is
incorporated herein by reference.
FIELD
[0002] The present disclosure relates generally to power transfer
systems configured to control the distribution of drive torque from
a powertrain to front and rear drivelines of four-wheel drive (4WD)
and all-wheel drive (AWD) motor vehicles. More specifically, the
present disclosure is directed to hypoid gearsets of the type used
in drive axle assemblies having features related to venting systems
and/or coupling systems.
BACKGROUND
[0003] This section provides background information related to the
present disclosure which is not necessarily prior art.
[0004] In view of increased consumer demand for four-wheel drive
(4WD) and all-wheel drive (AWD) motor vehicles, a large number of
power transfer systems are currently utilized in vehicular
applications for selectively and/or automatically transmitting
rotary power (i.e., drive torque) from the powertrain to all four
wheels. In most power transfer systems, a power transfer assembly
is used to deliver drive torque from the powertrain to one or both
of the primary and secondary drivelines. The power transfer
assembly is typically equipped with a torque transfer coupling that
can be selectively actuated to shift operation of the power
transfer system from a two-wheel drive mode into a four-wheel drive
mode. In the two-wheel drive mode, drive torque is only transmitted
to the primary driveline while drive torque can be transmitted to
both of the primary and secondary drivelines when the vehicle is
operating in the four-wheel drive mode.
[0005] In most 4WD vehicles, the power transfer assembly is a
transfer case arranged to normally transmit drive torque to the
rear driveline and selectively/automatically transfer drive torque
through the torque transfer coupling to the front driveline. In
contrast, in most AWD vehicles, the power transfer assembly is a
power take-off unit (PTU) arranged to normally permit drive torque
to be transmitted to the front driveline and to
selectively/automatically transfer drive torque through the torque
transfer coupling to the rear driveline.
[0006] Many power transfer assemblies are equipped with an
adaptively-controlled torque transfer coupling to provide an
"on-demand" power transfer system operable for automatically
biasing the torque distribution ratio between the primary and
secondary drivelines, without any input or action on the part of
the vehicle operator, when traction is lost at the primary wheels.
Modernly, such adaptively-controlled torque transfer couplings are
equipped with a multi-plate clutch assembly and a power-operated
clutch actuator that is interactively associated with an electronic
traction control system having a controller unit and a plurality of
vehicle sensors. During normal operation, the clutch assembly is
maintained in a released condition so as to transmit drive torque
only to the primary wheels and establish the two-wheel drive mode.
However, upon detection of conditions indicative of a low traction
condition, the power-operated clutch actuator is actuated to
frictionally engage the clutch assembly and deliver a portion of
the total drive torque to the secondary wheels, thereby
establishing the four-wheel drive mode.
[0007] In virtually all power transfer systems of the types noted
above, the secondary driveline is configured to include a
propshaft, a drive axle assembly, and one or more constant velocity
universal joints. Typically, the opposite ends of the propshaft are
drivingly interconnected via the constant velocity universal joints
to a rotary output of the torque transfer coupling and a rotary
input to the drive axle assembly. In most instances, this rotary
input is a hypoid gearset used to transmit drive torque from the
propshaft to a differential gear mechanism associated with the
drive axle assembly. The differential gear mechanism may include a
differential carrier rotatably supported in an axle housing and
which drives at least one pair of bevel pinions which, in turn, are
commonly meshed with first and second output bevel gears. The first
and second output bevel gears of the differential gear mechanism
are drivingly connected to corresponding first and second
axleshafts which, in turn, drive the secondary wheels. The hypoid
gearset includes a pinion gear meshed with a ring gear. The pinion
gear is typically formed integrally with, or fixed to, a solid
pinion shaft that is also rotatably support by the axle housing.
The pinion shaft is usually connected via one of the constant
velocity universal joints to the propshaft while the ring gear is
usually fixed for rotation with the differential carrier of the
differential gear mechanism. Due to the axial thrust loads
transmitted through the hypoid gearset, it is common to utilize at
least two laterally-spaced tapered bearing assemblies to support
the pinion shaft for rotation relative to the axle housing.
[0008] Many constant velocity (CV) joints are sealed in order to
retain lubricant, such as grease, inside the joint while keeping
contaminants and foreign matter, such as dirt and water, out of the
joint. To achieve this protection, the CV joint is typically
enclosed at the open end of its outer race by a sealing boot made
of rubber or urethane. The opposite end of the outer race is
sometimes formed by an enclosed dome or grease cap. Such sealing is
necessary since once the inner chamber of the CV joint is
partially-filled with the lubricant, it is generally lubricated for
life. It is often necessary to vent the CV joint in order to
minimize air pressure fluctuations which result from expansion and
contraction of air within the joint during operation. This is
especially true, for example, in tripod-type, plunging and
monoblock types of joints.
[0009] Plunging tripod CV joints are widely used in 4WD and AWD
vehicles and provide a plunging end motion feature which allows the
interconnected rotary components to change length during operation
without the use of splines. Plunging "cross-groove" types of CV
joints are also commonly used to interconnect the pinion shaft of
the hypoid gearset in the drive axle assembly to the propshaft and
include balls located in the circumferentially-spaced straight or
helical grooves formed in the inner and outer races. Typically.
CVJ's are vented by placing a vent system in the housing, such as a
vent hole, to allow passage of air into and out of the joint, as
needed, to prevent internal pressure buildups. Unfortunately,
grease may eventually block the air passage through the vent hole
which could lead to reduced service life of the lubricated for life
joints.
[0010] While such conventional drive axle assemblies and pinion
shaft support arrangements are adequate for their intended purpose,
a need still exists to advance the technology and structure of such
products to provide enhanced configurations that provide improved
efficiency, reduced weight, and reduced packaging requirements.
SUMMARY
[0011] This section provides a general summary of the disclosure
and should not be interpreted as a complete and comprehensive
listing of all of the objects, aspects, features and advantages
associated with the present disclosure.
[0012] It is an object of the present disclosure to provide an
arrangement and process for coupling an aluminum flange of a joint
coupling to a steel pinion shaft using an intermediary metal. The
aluminum flange can be coupled to a tubular portion of the steel
pinion shaft via various methods including, but not limited to,
brazing, welding, staking, splines and the like.
[0013] It is another object of the present disclosure to provide
venting solutions for venting axles, differentials and/or constant
velocity joints.
[0014] It is another object of the present disclosure to provide a
pinion cartridge design which can be threaded into an axle housing
to attach and set backlash between the pinion gear and the ring
gear of a hypoid gearset in a drive axle assembly.
[0015] It is yet another object of the present disclosure to
provide a hollow pinion gear/pinion shaft arrangement for a hypoid
gearset in a drive axle assembly.
[0016] These and other objects of the present disclosure are
provided by an integrated pinion/bearing/coupling (PBC) assembly
for use in a power transfer assembly to transfer drive torque from
a rotary input to a rotary output so as to transmit drive torque
from a powertrain to a pair of ground-engaging wheels. The PBC
assembly includes a pinion unit, a bearing unit, and a coupler
unit. The pinion unit is a hollow steel component having a pinion
shaft segment and a pinion gear segment which is adapted to be
meshed with a ring gear of a hypoid gearset. The coupler unit is an
aluminum component having a hub segment configured to surround an
end portion of the pinion shaft segment. The PBC assembly further
includes a brazing sleeve made of an intermediary material and
which is disposed between the hub segment of the aluminum coupler
unit and the hollow pinion shaft segment of the steel pinion unit.
A brazing operation is employed to rigidly and fixedly secure the
aluminum coupler unit for rotation with the steel pinion unit.
[0017] The PBC assembly of the present disclosure is further
configured such that the bearing unit includes a pair of
laterally-spaced bearing assemblies disposed between the pinion
shaft segment of the steel pinion unit and a bearing housing
adapted to be secured to a power transmission housing. A lock
collar can be integrated into the bearing housing of the bearing
unit to permit preload adjustment by varying the axial positioning
of the PBC assembly relative to the power transmission housing.
[0018] The PBC assembly of the present disclosure is further
configured to provide an internal venting arrangement installed
within the hollow steel pinion unit.
[0019] The PBC assembly of the present disclosure is well-suited
for use in drive axles and power take-off units such that the
pinion gear segment of the hollow steel pinion unit meshes with a
ring gear to define a hypoid gearset arrangement.
[0020] Further areas of applicability will become apparent from the
detailed description provided herein. The specific embodiments and
examples set forth in this summary are intended for purposes of
illustration only and are not intended to limit the scope of the
present disclosure.
DRAWINGS
[0021] The drawings described herein are only provided to
illustrate selected non-limiting embodiments and are not intended
to limit the scope of the present disclosure. According to the
following:
[0022] FIG. 1 is a schematic view of a four-wheel drive (4WD) motor
vehicle equipped with a power transfer system having one or more
products and/or assemblies embodying the teachings of the present
disclosure;
[0023] FIG. 2 is a diagrammatical illustration of a power transfer
assembly, embodied as a transfer case, associated with the 4WD
power transfer system shown in FIG. 1;
[0024] FIG. 3 is schematic view of an all-wheel drive (AWD) motor
vehicle equipped with a power transfer system having one or more
products and/or assemblies embodying the teachings of the present
disclosure;
[0025] FIG. 4 is a diagrammatical illustration of a power transfer
assembly, embodied as a power take-off unit, associated with the
AWD power transfer system shown in FIG. 3;
[0026] FIG. 5 is a diagrammatical view of an alternative version of
the all-wheel drive vehicle shown in FIG. 3 and which is equipped
with an AWD power transfer system having one or more products
and/or assemblies embodying the teachings of the present
disclosure;
[0027] FIG. 6 is a schematic view of a power transfer assembly,
embodied as a torque transfer coupling, associated with AWD power
transfer system shown in FIG. 5;
[0028] FIGS. 7A and 7B are sectional views of an integrated
pinion/bearing/coupling (PBC) assembly adapted for use with any of
the previously-noted power transfer systems and which is
constructed in accordance with the teachings of the present
disclosure, while FIG. 7C is a sectional view of a drive axle
assembly equipped with the PBC assembly;
[0029] FIG. 8 is an exploded isometric view showing an intermediate
sleeve and an aluminum flange plate associated with a mounting
system for the PBC assembly shown in FIG. 7;
[0030] FIG. 9 is an exploded isometric view showing a steel pinion
shaft and the aluminum flange plate for the mounting system
associated with the PBC assembly shown in FIG. 7;
[0031] FIG. 10 is a sectional view of an alternative embodiment of
a PBC assembly installed in a drive axle assembly and equipped with
a venting system arranged to vent air from the differential
assembly through the vented PBC assembly;
[0032] FIG. 11 illustrates an assembled isometric view of another
embodiment of a PBC assembly including a threaded pinion cartridge
assembly;
[0033] FIG. 12 is a sectional view of the PBC assembly shown in
FIG. 11 installed in an axle housing of a drive axle assembly;
and
[0034] FIG. 13 is a sectional view of a PBC assembly having an
alternative bearing arrangement constructed in accordance with the
present disclosure.
DETAILED DESCRIPTION
[0035] Example embodiments will now be described more fully with
reference to the accompanying drawings. The example embodiments are
provided so that this disclosure will be thorough, and will fully
convey the scope of the present disclosure to those who are skilled
in the art. In particular, various examples of different power
transfer systems for motor vehicles will be described to which
products and/or assemblies embodying the teachings of the present
disclosure are well-suited for use. To this end, various power
transfer assemblies including, without limitations, transfer cases,
power take-off units, drive axle assemblies, torque transfer
coupling, and differentials are disclosed which can be equipped
with a hypoid gearset having an integrated pinion/bearing/coupling
(PBC) assembly constructed in accordance with the teachings of the
present disclosure. However, numerous specific details are set
forth such as examples of specific components, devices, and
methods, to provide a thorough understanding of embodiments of the
present disclosure. It will be apparent to those skilled in the art
that specific details need not be employed, that example
embodiments may be embodied in many different forms and that
neither should be construed to limit the scope of the disclosure.
In some example embodiments, well-known processes, well-known
device structures, and well-known technologies are not described in
detail.
[0036] The terminology used herein is for the purpose of describing
particular example embodiments only and is not intended to be
limiting. As used herein, the singular forms "a," "an," and "the"
may be intended to include the plural forms as well, unless the
context clearly indicates otherwise. The terms "compromises,"
"comprising," "including," and "having," are inclusive and
therefore specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the
presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof. The
method steps, processes, and operations described herein are not to
be construed as necessarily requiring their performance in the
particular order discussed or illustrated, unless specifically
identified as an order of performance. It is also to be understood
that additional or alternative steps may be employed.
[0037] When an element or layer is referred to as being "on,"
"engaged to," "connected to," or "coupled to" another element or
layer, it may be directly on, engaged, connected or coupled to the
other element or layer, or intervening elements or layers may be
present. In contrast, when an element is referred to as being
"directly on," directly engaged to," "directly connected to," or
"directly coupled to" another element or layer, there may be no
intervening elements or layers present. Other words used to
describe the relationship between elements should be interpreted in
a like fashion (e.g., "between" versus "directly between,"
"adjacent" versus "directly adjacent," etc.). As used herein, the
term "and/or" includes any and all combinations of one or more of
the associated listed items.
[0038] Although the terms first, second, third, etc. may be used
herein to describe various elements, components, regions, layers
and/or sections, these elements, components, regions, layers and/or
sections should not be limited by these terms. These terms may be
only used to distinguish one element, component, region, layer or
section from another region, layer or section. Terms such as
"first," "second," and other numerical terms when used herein do
not imply a sequence or order unless clearly indicated by the
context. Thus, a first element, component, region, layer or section
discussed below could be termed a second element, component,
region, layer or section without departing from the teachings of
the example embodiments.
[0039] Spatially relative terms, such as "inner," "outer,"
"beneath," "below," "lower," "above," "upper," and the like, may be
used herein for ease of description to describe one element or
feature's relationship to another element(s) or feature(s) as
illustrated in the figures. Spatially relative terms may be
intended to encompass different orientations of the device in use
or operation in addition to the orientation depicted in the
figures. For example, if the device in the figures is turned over,
elements described as "below" or "beneath" other elements or
features would then be oriented "above" the other elements or
features. Thus, the example term "below" can encompass both an
orientation of above and below.
[0040] Referring initially to FIG. 1, an example of a four-wheel
drive (4WD) power transfer system for a motor vehicle 10 is shown.
Motor vehicle 10 includes a powertrain 11 operable for generating
and transmitting rotary power (i.e. drive torque) to a first or
primary driveline 18 and a second or secondary driveline 20.
Powertrain 11 is shown in this non-limiting example to include an
internal combustion engine 12 and a transmission 14. Primary
driveline 18, hereinafter identified as the rear driveline,
includes a pair of ground-engaging rear wheels 22 that are
interconnected via a pair of rear axleshafts 23 to a rear
differential assembly 24 as part of a rear drive axle assembly 26.
Secondary driveline 20, hereinafter identified as the front
driveline, includes a pair of ground-engaging front wheels 32 that
are interconnected via a pair of front axleshafts 33 to a front
differential assembly 36 defining a front drive axle assembly
36.
[0041] The power transfer system also includes a power transfer
assembly, shown in FIG. 1 as a transfer case 16, configured to
receive drive torque from powertrain 11 and transmit this drive
torque permanently to rear driveline 18 and
selectively/automatically to front driveline 20. Transfer case 16
generally includes a rear output shaft 30, a torque transfer
coupling 17, and a front output shaft 40. A first end of a rear
propshaft 28, also associated with rear driveline 18, is shown
drivingly connected via first joint coupling 27 to rear output
shaft 30. A second end of rear propshaft 28 is shown drivingly
coupled via a second joint coupling 29 to an input component 21 of
rear axle assembly 26. Typically, input component 21 is a pinion
shaft driving a pinion gear that is meshed with a ring gear, and
which together define a rear hypoid gearset. The ring gear drives
rear differential assembly 24. As such, rear propshaft 28 is
configured to transmit drive torque from rear output shaft 30 of
transfer case 16 to rear axle assembly 26. Similarly, a first end
of a front propshaft 38 associated with front driveline 20 is shown
drivingly connected via a first joint coupling 37 to front output
shaft 40. A second end of front propshaft 28 is shown drivingly
connected via a second joint coupling 39 to an input component 31
of front axle assembly 36. Typically, input component 31 is a
pinion shaft driving a pinion gear that is meshed with a ring gear,
and which together define a front hypoid gearset. The ring gear
drives front differential assembly 34. Thus, front propshaft 38 is
configured to transmit drive torque from front output shaft 40 of
transfer case 16 to front axle assembly 36.
[0042] Referring now to FIG. 2, a non-limiting example of transfer
case 16 will be described. In the arrangement shown, a transmission
output shaft 15 extends from a transmission housing 60 into a
transfer case housing 62 that is adapted to be secured to
transmission housing 60 and which defines an internal chamber 64.
Transmission shaft 15 is coupled for common rotation with rear
output shaft 30. Transfer case 16 is shown in FIG. 2 to further
include a transfer assembly 68 and torque transfer coupling 17 is
shown configured to include a clutch assembly 70 and a
power-operated clutch actuator 72. Transfer assembly 68 can be
configured as a geared drive assembly or as a chain drive assembly.
In the particular example disclosed, transfer assembly 68 is a
chain drive assembly having a first sprocket 74 drivingly coupled
to rear output shaft 30, a second sprocket 76 rotatably supported
on front output shaft 40, and a continuous power chain 78
encircling and meshing with both first sprocket 74 and second
sprocket 76. A coupling interface 79 is schematically shown for
indicating a drive coupling between first sprocket 74 and rear
output shaft 30.
[0043] Clutch assembly 70 is shown as a multi-plate friction clutch
having a first clutch member 80 coupled for rotation with second
sprocket 76, a second clutch member 82 coupled for rotation with
front output shaft 40, and a multi-plate clutch pack 84 comprised
of a plurality of interleaved inner and outer clutch plates. The
inner clutch plates are coupled to second clutch member 82 while
the outer clutch plates are coupled to first clutch member 80.
Power-operated clutch actuator 72 includes an axially moveable
apply device 88 capable of applying a compressive clutch engagement
force on clutch pack 84, and a powered driver unit 90 operable for
controlling the axial position of apply device 88 relative to
clutch pack 84. The magnitude of the clutch engagement force
exerted on clutch pack 84 is proportional to the amount of drive
torque transmitted from rear output shaft 30 through transfer
assembly 68 to front output shaft 40. Accordingly, when a
predetermined minimum clutch engagement force is applied to clutch
pack 84, a minimum amount of drive torque is transmitted to front
driveline 20. In contrast, when a predetermined maximum clutch
engagement force is applied to clutch pack 84, a maximum amount of
drive torque is transmitted to front driveline 20. As such,
adaptive control over the front/rear drive torque distribution
ratio can be provided by actively controlling operation of transfer
case 16 to establish a two-wheel drive (2WD) mode and an on-demand
four-wheel drive (4WD) mode. FIG. 2 also illustrates a transfer
case controller unit 48A associated with vehicle controller 48 of
FIG. 1 that is operable for controlling actuation of powered driver
unit 90 in response to signals from sensors 44 and/or mode selector
46 and which, in turn, controls the axial position of apply device
88 relative to clutch pack 84.
[0044] Referring now to FIG. 3, an example of an all-wheel drive
(AWD) power transfer system for a motor vehicle 10' is shown. Motor
vehicle 10' includes a powertrain 11' comprised of an engine 12'
and a transmission 14'. The primary driveline, in this non-limiting
example, is front drlveline 20' while the secondary driveline is
rear driveline 18'. Drive torque from powertrain 11' is normally
transmitted through a front differential assembly 34' to front
wheels 32 via front axleshafts 33. As seen, the first end of a rear
propshaft 28' is drivingly interconnected via first joint coupling
27 to an output component 91 of a power transfer assembly,
hereinafter referred to as power take-off unit 90. Furthermore, the
second end of rear propshaft 28' is drivingly connected via second
joint coupling 29 to rotary input 21 of rear axle assembly 26.
[0045] FIG. 4 diagrammatically illustrates a non-limiting example
of power take-off unit (PTU) 90. A final drive gearset 92 of
transmission 14' includes an output gear 94 driving a ring gear 96
fixed to a differential carrier 98 of front differential assembly
34'. PTU 90 includes an input shaft 100 driven by gearset 92 or
carrier 98, a hypoid gearset 102, and a torque transfer coupling
17' therebetween. Hypoid gearset 102 includes a crown gear 104
meshed with a pinion gear 106 which, in turn, is drivingly
connected to a pinion shaft 108 which acts as output component 91.
Torque transfer coupling 17' includes a clutch assembly 70' and a
power-operated clutch actuator 72'. Clutch assembly 70' is a
multi-plate friction clutch having a first clutch member 80'
coupled to input shaft 100, a second clutch member 82' coupled to
crown gear 104, and a multi-plate clutch pack 84'. Multi-plate
clutch pack 84' includes inner clutch plates coupled to first
clutch member 80' which are alternately interleaved with outer
clutch plates coupled to second clutch member 82'.
[0046] Power-operated clutch actuator 72' includes an
axially-moveable apply device 88' capable of applying a compressive
clutch engagement force on clutch pack 84', and a powered driver
unit 90' operable for controlling the axial position of apply
device 88' relative to clutch pack 84'. The magnitude of the clutch
engagement force applied to clutch pack 84' is proportional to the
amount of drive torque transmitted from input shaft 100 through
clutch assembly 70' and hypoid gearset 102 to rear propshaft 28'.
Thus, when a minimum clutch engagement force is applied to clutch
pack 84', a minimum drive torque is transmitted via hypoid gearset
102 to rear driveline 18'. In contrast, when a maximum clutch
engagement force is applied to clutch pack 84', a maximum drive
torque is transmitted to rear driveline 18'. As such, active
control over the front/rear torque distribution ratio is provided.
This allows establishment of the above-noted 2WD and on-demand 4WD
modes of operation for vehicle 10'.
[0047] Referring now to FIG. 5, a revised version of AWD motor
vehicle 10' is now shown with torque transfer coupling 17' removed
from PTU 90' and operably disposed between rear propshaft 28' and
rotary input 21 to rear axle assembly 26. As such, PTU 90' is
configured with input shaft 100 driving crown gear 104 of hypoid
gearset 102 such that pinion gear 106 drives rear propshaft 28' via
coupling unit 27. As best seen from FIG. 6, rotary input 21 of rear
axle assembly 26 is shown to include a pinion shaft 110 and a
hypoid gearset 112. Pinion shaft 110 is fixed to second clutch
member 82' of clutch assembly 70'. Hypoid gearset 112 includes a
pinion gear 114 meshed with a ring gear 116. Pinion gear 114 is
fixed to pinion shaft 110 while ring gear 116 is fixed for rotation
with a carrier 120 of rear differential assembly 24. Rear
differential assembly 24 is shown to include a pair of differential
pinions 122 rotatably mounted on crosspins 124 that are fixed to
carrier 120. Output gears 126 are meshed with pinions 122 and are
drivingly connected to axleshafts 23. Actuation of power-operated
clutch actuator 72' functions to control the amount of drive torque
transmitted from powertrain 11' through PTU 90' and rear propshaft
28' to hypoid gearset 112 for driving rear axle assembly 26.
[0048] The above configurations are clearly illustrated to
incorporate a hypoid gearset into one or more products and/or
assemblies associated with rear axle assembly 26, front axle
assembly 36, torque transfer device 17' and/or PTU 90, 90'.
Accordingly the following detailed description of various
embodiments of the present disclosure is sufficient to provide one
skilled in this art an understanding and appreciation of the
structure and function of the following.
[0049] Referring now to FIGS. 7 through 9, an integrated
pinion/bearing/coupling arrangement, hereinafter referred to as a
PBC assembly 150, is shown to generally include a pinion unit 152,
a coupler unit 154, a bearing unit 156, and a threaded lock collar
unit 158. Pinion unit 152 is configured as a hollow steel component
(preferably forged) having a tubular pinion shaft segment 160 and a
tubular pinion gear segment 162. While shaft segment 160 and gear
segment 162 are shown to be integrally formed as a homogeneous
steel component, it will be understood that pinion gear segment 162
can alternatively be a separate hollow component (made of different
material) that is rigidly secured to a first end of pinion shaft
segment 160. Shaft segment 160 has a first end portion 164 from
which gear segment 162 extends and a second end portion 166 having
an end surface 168. Bearing unit 156 includes a pair of
laterally-spaced bearing assemblies 169A, 169B that are operably
installed between an intermediate portion 170 of pinion shaft
segment 160 and a bearing housing 172 configured to be installed in
a pinion housing portion 153 of an axle housing 155. Bearing
housing 172 functions to axially position bearing assemblies 169A,
169B. As best seen in FIG. 7B, bearing housing 172 includes a
radially-inwardly extending cylindrical lug 173 against which the
outer races of bearing assemblies 169A, 169B are engaged. Bearing
housing 173 further includes fluid ports 175A, 175B provided to
facilitate lubrication supply to the bearings.
[0050] Lock collar unit 158 is rigidly secured to bearing housing
172 (or formed integrally therewith) and includes external threads
174 provided to permit the axial positioning of PBC assembly 150 to
be adjusted relative to pinion housing portion 153 of axle housing
155 for setting desired preload and/or backlash between gear teeth
176 on gear segment 162 of pinion unit 152 and gear teeth 173 on a
ring gear 175. A sealing arrangement includes a seal plate 180
fixed to coupler unit 154 and a flexible rotary seal 182 disposed
between seal plate 180 and lock collar 158. A grease cap 184 is
shown installed within second end portion 166 of shaft segment
160.
[0051] FIG. 7C illustrates a version of one of rear drive axle 26
and front drive axle 36 equipped with PBC assembly 150. As shown,
axle housing 155 also includes a differential housing portion 157
defining a differential gearset chamber 159 which communicates with
a pinion chamber 161 formed in pinion housing portion 153.
Differential assembly 24, 34 includes a differential carrier 163 to
which ring gear 175 is rigidly secured (i.e. welded) for common
rotation. Carrier 163 is rotatably supported in differential
housing portion 157 of axle housing 155 via a pair of
laterally-spaced differential bearing assemblies 165, 167. A
differential gearset is operably installed within differential
gearset chamber 159 of carrier 163 and includes a pair of
differential pinions rotatably supported on crosspins that are
fixed for rotation with carrier 163. The differential gearset
further includes a pair of differential output gears each of which
is meshed with both differential pinions. As is conventional, the
differential output gears are drivingly connected to axleshafts
23/33. The exemplary drive axles are shown to illustrate a hypoid
gearset comprised of pinion gear segment 162 and ring gear 175 and
further illustrate the advantages associated with PBC assembly 150
to be described hereinafter.
[0052] Coupler unit 154 is shown to include a flange plate 190
having a tubular hub segment 192 and a radial disk segment 194.
Disk segment 194 has a planar mounting face surface 196 configured
to mate with a corresponding coupling component of a joint unit
(i.e. constant velocity joint) or with a mounting flange of a
propshaft. A plurality of mounting bores 198 are formed through
disk segment 194 and are configured to accept threaded fasteners
provided for rigidly connecting coupler unit 154 to the
corresponding coupling component. Hub segment 192 defines an inner
diameter surface 200 having an annular groove 202 formed therein
and an end groove 204. Coupler unit 154 is preferably manufactured
from aluminum such as, for example, 6000 or 7000 series aluminum
and/or aluminum alloys.
[0053] Coupler unit 154 is also shown to include an intermediate
sleeve, hereinafter referred to as brazing sleeve 210, having a
tubular sleeve segment 212 and a raised end flange segment 214.
Sleeve segment 212 is configured to include an inner diameter
surface 216 sized to rest on an outer diameter surface 218 of
second end portion 166 of pinion shaft segment 160, and an outer
diameter surface 220 sized to engage surface 200 of hub segment
192. As best seen in FIG. 7A, raised end flange segment 214 of
brazing sleeve 210 is configured to be aligned and retained in end
groove 204 of hub segment 192 on flange plate 190. Brazing sleeve
210 is preferably made of a copper or copper/brass alloys or
zinc/zinc alloys and is adapted to establish a bonded (i.e. brazed)
connection between hub segment 192 of aluminum coupler unit 154 and
end portion 166 of steel pinion shaft segment 160. Surface 200 of
hub segment 192 can be modified prior to the brazing process to
form a layer (i.e. zinc or other coating material) to reduce or
eliminate intermetallic layer post welding operation.
[0054] The arrangement shown in FIGS. 2 through 9 provides a method
and configuration for attaching an aluminum flange to a hollow
steel pinion shaft while maintaining a desired pinion bearing
preload. Specifically, the use of brazing sleeve 210 fabricated
from an intermediary material (copper, copper/bronze alloys,
zinc/zinc alloys, etc.) facilitates the laser brazing of an
aluminum flange to a steel pinion shaft. Brazing of this joint
allows for the accurate setting of the pinion bearing preload with
the aluminum flange since large diameter hollow gear segment 162
and shaft segment 160 allows for such a joining process since the
shear stress at these larger diameters drive by torque is
relatively low. This arrangement may also result in elimination of
propshaft flange balancing requirements, simplified assembly, and
improved preload accuracy with welded/brazed pinion for increased
efficiency.
[0055] The hollow pinion design was developed specifically to
optimize the overall weight of the axle assembly. Traditional axle
pinions typically consist of a gear portion and solid stem portion
which is supported by bearings. Due to the relatively small
diameter of the stem portion and therefore the bearings, the
bearings need to be spaced axially apart a certain distance to
maintain stiffness or need to incorporate an additional bearing at
the head (the gear section) of the pinion. This results in an
increased length axle housing. In this application, designing a
hollow pinion with a large diameter equal to approximately 50% of
its overall length improved mass by over 20%. This design maintains
the same stiffness while also improving the stresses within the
bearing as the number of balls are increased at this larger
diameter. This also allows for use of thinner and lighter bearing
assemblies. Torque transfer capability thru the hollow pinion is
equivalent to a smaller diameter solid stem pinion due to increased
polar moment of inertia. This improved cross section allows the
wall thickness to be further optimized for maximum weight
savings.
[0056] Referring now to FIG. 10, an alternative version of PBC
assembly 150 will be described and hereinafter referred to as
"vented" PBC assembly 250. Since vented PBC assembly 250 is
generally similar in construction and operation to that of PBC
assembly 150, common reference numerals are used to identify those
components that are similar to those previously described. In
general, vented PBC assembly 250 is adapted to be mounted within a
pinion housing portion 252 of an axle housing 254 and includes
pinion unit 152, coupler unit 154, bearing unit 156, and threaded
lock collar unit 158. Threads 174 on lock collar unit 158 are shown
in threaded engagement with internal threads 256 formed in pinion
housing portion 252 of axle housing 254. Seal rings 255, 257 are
provided between integrated lock collar 158--bearing housing 172
and pinion housing 252. Pinion teeth 176 on gear segment 162 of
pinion unit 152 are shown meshed with gear teeth 260 formed on a
ring gear 262 which, in turn, is fixed to differential carrier 120
of differential assembly 24. Lateral differential bearing
assemblies 264 rotatably support differential carrier 120 on a
differential housing portion 266 of axle housing 254. As seen, a
pinion chamber 268 formed in pinion housing portion 252
communicates with a differential chamber 270 formed in differential
housing portion 266.
[0057] Typically, a vent system is provided in association with
differential housing portion 266 of axle housing 254 to provide a
vent passage between differential chamber 270 and ambient. However,
the present disclosure is directed, in this particular embodiment,
to a venting system associated with vented PBC assembly 250 to vent
air from within differential chamber 270 and/or pinion chamber 268
to atmosphere through a vent assembly 280 that is installed within
hollow shaft segment 160 of pinion unit 152. This new and improved
venting arrangement permits elimination of conventional
differential housing vent systems and provides a sealed arrangement
preventing water from being drawn into axle housing 254 upon
submerging thereof, thereby meeting OEM "fording" requirements.
[0058] With continued referenced to FIG. 10, vent assembly 280 is
shown installed in a central aperture 282 formed in a tubular
segment 283 of a grease cap 184' mounted to an inner wall surface
284 of second end portion 166 of pinion shaft segment 160. A valve
seat ring 286 is installed in central aperture 282 and defines a
valve seat opening 288. A spring-loaded plunger 290 is moveable
relative to valve seat opening 288 to control the flow of
pressurized air from inside hollow pinion unit 152 to atmosphere,
as indicated by the arrow 294. Location of vent assembly 280 to
within pinion unit 152 of PBC assembly 250 provides additional
protection in comparison to conventional housing mounted vents
since it is now protected from external damage and fouling.
[0059] FIGS. 11 and 12 better illustrate a cartridge type pinion
assembly 348 used in PBC assembly 150 and/or 250. A combined
locking collar 158 and bearing housing 172, hereinafter "cartridge"
400, integrates the function of both into a stand-alone assembly.
Cartridge 400 includes lubrication slots 402 and ports 404
providing lubrication to bearing 169A, 169B while a separator ring
406 maintains spacing therebetween. Threads 408 permit a threaded
connection to pinion housing portion of axle housing which, in
turn, permits precise axial positioning of the pinion assembly for
optimized backlash setting. This threaded arrangement eliminates
use of shims, and reduces housing stresses for permitting weight
savings.
[0060] Referring to FIG. 13, another alternative embodiment of PBC
assembly 450 is shown to include pinion unit 152, coupler unit 154,
a bearing unit 452 and a threaded cartridge unit 454. Bearing unit
452 is shown to include a first axial thrust needle bearing 456
disposed between a first edge 458 of cartridge 454 and coupler unit
154, a second axial thrust needle bearing 460 disposed between a
second edge 462 of cartridge 454 and gear segment 162 of hollow
pinion unit 152, and a radial needle bearing 464 disposed between
an inner diameter surface 466 of cartridge 454 and an outer
diameter surface 468 of intermediate portion 170 of shaft segment
160. Threads 158 on cartridge 454 permits axial adjustment of PBC
assembly 450 relative to the pinion housing portion of the axle
housing. This arrangement of needle (axial and radial) bearings in
place of conventional bearings provides weight reduction while
providing equivalent stiffness and reduced drag losses,
particularly in combination with a hollow pinion unit.
[0061] The foregoing description of the embodiments has been
provided for purposes of illustration and description. It is not
intended to be exhaustive or to limit the disclosure. Individual
elements or features of a particular embodiment are generally not
limited to that particular embodiment, but, where applicable, are
interchangeable and can be used in a selected embodiment, even if
not specifically shown or described. The same may also be varied in
many ways. Such variations are not to be regarded as a departure
from the disclosure, and all such modifications are intended to be
included within the scope of the disclosure.
* * * * *